The invention relates to a catheter, in particular for endovascular applications, comprising a long and flexible, hollow, tubular body having an insertion end and a connection end intended to remain outside the body.
In the medical field it is known that there exists the need to carry out suitable procedures for the treatment of vessels which are obstructed—at least over part of their diameter—by constrictions, or so-called “stenoses”, arteriosclerotic plaques with or without superimposed thrombi, or the like, in order to restore the complete accessibility and functionality thereof. Said stenoses may hinder or even prevent the normal flow of substances which physiologically pass through the vessels. In particular in the case of the carotid artery, said stenoses may hinder or even prevent the normal flow of blood towards the organs in the head such as, for example, the brain and the eyes. Said stenoses may also release fragments of plaque or thrombi with the possibility of serious embolisms affecting the abovementioned organs.
Normally these types of pathologies are dealt with by means of external surgery. Said surgery involves the incision of the skin and the underlying layers and isolation of the section of artery affected by the stenosis; it also involves clamping the artery itself, which is performed upstream and downstream of the stenosis so as to block the circulation temporarily. In particular, in the case of the carotid artery, said clamping is normally performed upstream and downstream of the carotid bifurcation, i.e. on the common carotid, on the internal carotid and on the external carotid. At this point it is envisaged operating on the section affected by the stenosis using the appropriate procedures which envisage removal of the obstructing plaque through the opening of the artery section concerned, which is then carefully cleaned and sewn up again directly or by means of application of a prosthetic widening tissue (called “patch”). The surgical method involves, however, closure of the section of the carotid artery operated on with interruption of the blood flow for a period of time of about 15-30 minutes. During this period of time, the flow of blood to the brain is compensated for by the flow coming from other arteries directed towards the brain.
In 10-15% of cases this compensation of the blood flow is not sufficient and, after just 9 minutes of clamping, serious damage to the brain may occur. To avoid this, it is necessary to carry out extremely rapid operations with the risk of imprecision, or apply special devices consisting of temporary bridges (or “shunts”) which are applied downstream of the section of carotid artery which is obstructed. These devices, however, cause an obstruction in the operating zone and may cause complications and, for these reasons, are used only if absolutely necessary. In order to identify the cases where shunts are required, numerous systems have been developed for monitoring the state of the brain or the cerebral blood flow. These systems are not devoid of errors or inaccuracies, so that many surgeons use the method of brain monitoring while operating on the patient in the conscious state and under a local anaesthetic. This method, which is the safest for avoiding brain damage during the operation, has the drawback that it subjects the patient to a great deal of stress and often is very painful, in particular in the case of patients with particular anatomical forms (“bull neck”) or who have carotids affected by lesions or carotid bifurcations which are situated very high in the neck. The operation also involves the possibility of damage to the nerves in the neck, in particular in the case of repeated operations or necks subjected to radiotherapy, with unpleasant post-operative consequences.
In view of the above situation, for several years now there has been the need to provide a new instrument for therapeutic treatment which allows treatment of pathologies such as those described or similar pathologies, using procedures which are less invasive or not invasive at all, in order to reduce as far as possible the risks for the patient, associated with a surgical operation. For this purpose, in about the year 1980, Matias was the first person to transfer the techniques of endoluminal dilation of the peripheral arteries to the carotid arteries. These techniques involve positioning a guide wire beyond the stenoses. A catheter eguipped with an inflatable element (commonly called a “balloon”) is then passed along the guide wire and the inflatable element is expanded in the region of the stenosis in order to dilate it. This method has been successful, but also involves many complications due to thromboses or embolisms.
The results have improved with the use of elements, called “stents”, which consist in tubular shaped meshwork structures which have the task of supporting the dilated section, holding in place the thrombus and plaque fragments. Despite this, the number of unsuccessful results have still been high. In order to avoid embolisms during the procedure, guide wires provided with a “balloon” to be applied inside the internal carotid artery, or a supporting catheter provided with an expandable element (or “balloon”) to be applied to the common carotid artery, have beer developed. These methods, however, are unable to prevent possible embolisms during the endoluminal manoeuvre since they do not provide protection during the initial stages of insertion of the guide wires (“Teron” method) and moreover they do not exclude the flow towards the brain through the external carotid artery.